TRAVERSE CITY, Mich. (AP) -- A debris field at the bottom of Lake Michigan may be the remains of the long-lost Griffin, a vessel commanded by a 17th-century French explorer, said a shipwreck hunter who has sought the wreckage for decades.

Steve Libert told The Associated Press that his crew found the debris this month about 120 feet from the spot where they removed a wooden slab a year ago that was protruding from the lake bottom. Libert believes that timber was the bowsprit of Rene-Robert Cavelier, Sieur de La Salle's ship, although scientists who joined the 2013 expedition say the slab more likely was an abandoned fishing net stake.

He described the bottomland area as littered with wooden planks that could belong to a ship's bow, along with nails and pegs that would have fastened the hull to the rest of the vessel and what appeared to be sections of a mast.

He acknowledged his dive team had found no "smoking gun" such as a cannon or other artifacts with markings identifying them as belonging to the Griffin. But the nails and other implements appeared similar to those from La Belle, another of La Salle's ships that sank near the Gulf of Mexico, Libert said.

He said his organization has sent images of the debris to three French underwater archaeologists who took part in last year's search. They plan to seek state and federal permits to excavate in the area in September, Libert said.

Dean Anderson, Michigan's state archaeologist, said Monday he hadn't been notified of the find and could not speculate about whether the Griffin had finally been located. Anderson supports the theory that the timber discovered earlier was a fishing apparatus.

The area strewn with debris is roughly the size of a football field, said Brian Abbott of Nautilus Marine Group, who joined Libert's search this month and took sonar readings of the bottomlands. It is near tiny Poverty Island in northwestern Lake Michigan and about 50 feet below the water's surface.

The Griffin is believed to be the first ship of European design to sail the upper Great Lakes. It disappeared with a crew of six on its maiden voyage in 1679 after La Salle had disembarked near the mouth of Wisconsin's Green Bay.